That seems really unprofessional to me. In nearly any on-the-job setting, whether on the ground, in the air or on the ocean, reading even mildly sexual material while at work is not considered acceptable. While he may have had a moment of downtime, he was still on the clock and not on any sort of official break even. While in uniform he's a representative of the airline, and I'm sure they wouldn't want one of their employees looking at that kind of material on their dime.

Reminds me of a manager at a job I had who was canned for looking at something equivalent to the Sports Illustrated Swimsuit models while at work. One of his reports was offended when she walked up behind him and saw what he was looking at. I suspect that this guy had a few other unrelated black marks on his record, and this was the final straw. Still, it seems a bit extreme, and goes to show how careful companies are being these days.